This research has focussed on the carcinogenicity, mode of action and binding of trichloroethylene (TCE) to tissue constituents by in vitro studies using microsomal preparations from various organs. Because of the industrial importance and possible environmental dispersion of TCE and its analogs, studies will be continued along the above lines. The compounds to be included in the continuation of this program are: methylene chloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane and hexachloroethane. These studies are of importance because of the potential human health hazards not only in the workplace but in the environment.